1. Field of the Invention
The present invention concerns a solid state p-n heterojunction, comprising an electon conductor and a hole conductor. The invention concerns also a solid state sensitized photovoltaic cell, in particular a solar cell.
2. Description of Related Art
The dye sensitized solar cells (DYSC), are more and more maturing into a technically and economically credible alternative to the conventional p-n junction photovoltaics. Photoelectrochemical (PEC) liquid junction cells based on the photosensitization of semiconductor TiO2 layers with molecular sensitizers attracted renewed interest after Graetzel et al reported energy conversion efficiencies >10%, in Nature, 353 (1991) 737. In 1998, Graetzel et al reported in Nature, 395 (1998) 583, a more innovative all solid state cell based on a heterojunction sensitized by a molecular dye where an amorphous organic hole transport material replaced the liquid electrolyte.
The crucial part in these cells is the dye itself. Only a very limited number of dyes give high photocurrent quantum yields and are reasonably stable against photo-degradation. Some of the organic dyes exhibiting high light absorption are sensitive to air and water.
It is therefore a target of the present invention to propose photovoltaic cells having improved stability against photo-degradation and environmental influences. It is another target of the invention to achieve higher photocurrent quantum yields, higher photovoltages and hence higher conversion yields in the visible part of the light spectrum.